What is the difference between burnup and depletion calculations?

catseye747

What is the difference between burnup calculations and depletion calculations?

Astronuc

They are the same. Burnup refers to the energy produced per unit mass of fuel, usually in MWd/kgU or GWd/tU, although the Canadians like to use MWh/kgU, the Belgians and some others used to use MWd/kgUO[sub]2[/sup], and for a long time GE (GNF) used GWd/stU (st = short ton). In MOX cores, the burnup may expressed in GWd/tHM (HM=Heavy Metal, U+Pu). Finally some folks used FIMA, or fissions per initial metal atom, with a rough equivalence of 1% FIMA = 9.75 GWd/tU.

The term depletion refers to the reduction or depletion of enrichment of the fuel. When fuel is irradiated, most of the fission event occur in U-235 until sufficient Pu-239/Pu-240/Pu-241 build up to compete with the U-235 for neutrons.

Using a code like SIMULATE, one does core depletion calculations which basic simulate the fission process in the core during a cycle of operation.